Warcraft II is a fantasy-themed real-time strategy (RTS) game published by Blizzard Entertainment and first released for MS-DOS in 1995 and for Mac OS in 1996. The main game, Warcraft II: Tides of Darkness, earned enthusiastic reviews, won most of the major PC gaming awards in 1996, and sold millions of copies. The rivalry between Blizzard's series and Westwood Studios's Command & Conquer series fueled the RTS boom of the late 1990s. Later in 1996 Blizzard released an expansion pack Warcraft II: Beyond the Dark Portal for MS-DOS and Mac OS, and a compilation Warcraft II: The Dark Saga for the Sony PlayStation and Sega Saturn. The Battle.net Edition, released in 1999, provided Blizzard's online gaming service, Battle.net, and replaced the MS-DOS version with a Windows one.